FAILURE MODE AND EFFECTS ANALYSIS (FMEA)

FAILURE MODE AND EFFECTS ANALYSIS

Entire process of FMEA development, either design or process, uses a common approach to address as per the guidelines provided in the AIAG Reference Manual: IV Edition of FMEA.

NEW PRODUCT DEVELOPMENT OF PROCESS FMEA:  
Prepare a flow chart. This Flow chart should identify the
Product/ Process Characteristics associated with each
operation as finalized by CFT at the time of product
realization process.

Carry out risk assessment and conduct FMEA for all high risk Process steps. Copy of Flow Chart/ risk assessment should accompany the process FMEA.

Document the Potential failure and their consequences in the FMEA format. The usage of this format is given below with number correlating with number given on the format.

Following items to be considered while forming FMEA
•  Troubles in the past of Similar Part.
•  Defect items expected (PFMEA Matrix)
•  Defect items unable to capture at customer end
•  Defect items difficult to repair
•  Defect Matrix (Past 6 months’ data)
•  PFD
•  Customer Specific Requirement
•  Similar Part PFMEA
•  AIAG SOD Ranking

FMEA NUMBER - Enter the FMEA document number as per the numbering system described

ITEM – Enter the name and number of the part for which the process is being carried out.

PROCESS RESPONSIBILITY – Enter the Section / Department responsible for maintaining the process

PREPARED BY – Enter the name of the CFT leader and his signature


FMEA DATE – Enter the date when the original FMEA was compiled and the revision dates as and when the FMEA undergoes revision

CORE TEAM - Enter the names of Team members, their department and designation

PROCESS FUNCTION / REQUIREMENT -Enter a simple description of the process/operation being analyzed. Indicate as concisely as possible the purpose of the process or operation being analysed.
Example: - Press Operation

POTNTIAL FAILURE MODE – Enter the Potential failure mode for each process requirement separately by asking how the process/component can fail to meet the process requirement. The assumption is that the failure could occur but may not necessarily occur.
Example – Dia more, Dia less etc.

POTENTIAL EFFECT OF FAILURE – Enter the Potential effect of failure i.e., the effect of failure mode on the customer. The customer may be next operation or end user. Each must be considered when assigning the Potential effect of failure.
Example: For next operation turning, Customer Dissatisfaction etc.

SEVERITY (S) – Severity is an assessment of the seriousness of the effect of the potential failure mode to the internal or external customer. Severity is estimated in 1 – 10 scale as per FMEA severity reference table.

CLASSSIFICATION- Indicate the classification of special characteristics by the use of Symbol finalized by CFT / customer

POTENTIAL CAUSES / MECHANISM OF FAILURE- List to the extent possible, each and every conceivable failure causes assignable to each potential failure mode. Describe the cause in terms of something that can be corrected or can be controlled.
Assume all inputs are conforming to specification and process design of the product is acceptable during first interaction.

Ambiguous phrases like operator error, machine malfunction, etc., should be avoided. List out first level causes like Man, Machine, Method, Material etc., and write the root cause under each first level causes. Typical examples are Tool Wear, Improper set up, inaccurate gauging etc.
For failure, which has no direct relation to a cause, a cause and Effect diagram should be drawn.
While generating the causes, the potential failure only should be considered not the effects. Refer the historical Quality records to verify that all causes occurred are listed.

OCCURANCE (O) - Occurrence is how frequently the specific failure cause is projected to occur. Estimate the likelihood of occurrence of a cause on 1 to 10 scales as per FMEA Manual. Only occurrence resulting in the failure mode should be considered for ranking. Failure detecting measures should not be considered here.

CURRENT PROCESS CONTROL- Enter the proposed or current controls that detects the failure mode, should it occur, or prevent the failure mode for occurring.

The types of Control are:

TYPE 1 Prevent the cause or failure from occurring. (e.g. Mistake proofing)

TYPE 2 Detect the cause mechanism and lead to corrective action (e.g. SPC charts, set up approval etc.)

TYPE 3 Detect the failure mode (e.g. 100% inspection at stage or during the subsequent operations)

The control should be written against each cause listed in potential causes Column. If no control on the causes, then write “No Control’.

All Controls listed should be presently being practiced in the process and should be referred in any of the documents such as Control Plans, Work Instruction etc.

Estimate the detection ranking on 1-10 scale from FMEA Manual. The controls such as control charts, 100% inspection, and sampling done on statistical basis is valid detection control and deserves low ranking. The low occurrence does not deserve low detection ranking.

Random Quality checks are unlikely to detect the existence of an isolated defect. Sampling done on a statistical basis is a valid detection

RISK PRIORITY NUMBER (RPN) – The risk priority number is the product of Severity, Occurrence and Detection.

RPN = (S) X (O) X (D)

The RPN will be in between 1 to 1000. For higher RPN, the team must undertake efforts to reduce the risk through corrective actions. In general, regardless of the resultant RPN, special attention should be given when the severity of potential effect of failure is high.

RECOMMENDED ACTION- After completion of the steps described above, the RPN are to be analyzed in Pareto fashion to identify the priority for control.

To reduce the probability of occurrence, process revisions are required.

The actions recommended should be to prevent / eliminate the causes to reduce the occurrence ranking. The preventive techniques, such as, mistake proofing methodology, SPC method to be considered.

RESPONSIBILITY AND TARGET TO COMPLETE - Enter the department / individual responsible for the recommended action and the target date of completion.

ACTION TAKEN- After an action has been taken, enters the brief description of the action taken and effective date.

ACTION RESULTS – After the corrective action taken, the Team Leader is to verify the action for implementation. Estimate and record the resulting S, O, D ranking. Calculate the RPN. If no action is taken leave the related ranking column blank. 

All resulting RPN should be reviewed and if further action is considered necessary, repeat step-18 through step 21

FMEA REVIEW AND UPDATING:  

QA Head will review FMEA once yearly basis as per plan.

Action shall be taken on

• Top 1 RPN

• Severity 9 & 10 resulting in RPN >100

FMEA is a living document and should always reflect the latest changes and incorporation in the process. 

FMEA should be reviewed whenever

• Process is changed, 

• Engineering Change

• In-house complaint

• Customer Complaint

Whenever FMEA is reviewed, the concerned process related documents like Control plans, Stage Drawings, Work Instructions etc. are to be reviewed and updated if required.